This invention relates to a loudspeaker device of a stereophonic dipole system (hereinafter referred to as xe2x80x9cSD systemxe2x80x9d in which no acoustic short-circuiting takes place in a case where left side and right side loudspeakers are disposed in close proximity to each other.
In a conventional loudspeaker device for stereophonic audio reproduction, left side and right side loudspeakers are disposed in front of a listener and with a certain distance provided between the two loudspeakers.
A loudspeaker device called SD system has recently been proposed. A brief explanation will be made about the reproduction principle of the SD system.
The SD system is basically composed of a digital filter network inserted immediately before an amplifying power amplifier in the reproduction system and two loudspeakers disposed in front of a listener in close proximity to each other. The digital filter network corresponds to standard stereophonic, monaural and binaural sources as their input sources. For these input signals, the digital filter network has a function of cancelling a crosstalk sound which reaches from the right channel to the left channel (or from the left channel to the right channel) and produces two channel outputs after subjecting the input signals to this filtering processing. By amplifying these outputs and supplying them to the two loudspeakers which are disposed in front of a listener in close proximity to each other for reproduction, a virtual reality sound field space is produced in front of the listener. This SD system is advantageous in that, in comparison with the conventional loudspeaker device, it has a broader listenable area and a broader allowable range for moving of the listener""s head during reproduction.
Further, as a result of passing through the above described digital filter network, the output sound reaches the listener""s ear with the harmful component called the crosstalk sound being cancelled, so that a high fidelity reproduction of music can be realized.
In the above described SD system, however, there occurrs a problem that, since the loudspeakers are disposed in close proximity to each other, opposite phase components of left and right channel signals are acoustically short-circuited to cancel each other in the vicinity of loudspeaker units immediately after generation of these signals and, therefore, these components do not reach the listener""s ear. Particularly, occurrence of this phenomenon in middle and low frequency sound ranges which have a broad directivity in reproduction prevents propagation of a reproduced sound over a broad range and also reduces the sound pressure level of a reproduced sound in the middle and low frequency sound ranges.
It is, therefore, an object of the invention to provide a loudspeaker device of the SD system in which opposite phase components of left and right channel signals do not cancel each other.
For achieving the above described object of the invention, there is provided a loudspeaker device comprising left and right channel loudspeaker units which are disposed on left and right sides in close proximity to each other, and a partition member projecting forwardly in the direction of propagation of sound from the loudspeaker units by a predetermined distance from a position between the loudspeaker units on a plane of a baffle on which the loudspeaker units are mounted.
In one aspect of the invention, in the loudspeaker device, said left and right channel loudspeaker units are respectively mounted on independent loudspeaker enclosures and these left and right loudspeaker enclosures which constitute a pair are disposed adjacent to each other to be integrated together and said partition member is disposed on a plane on which the loudspeaker enclosures are disposed adjacent to each other.
In another aspect of the invention, there is provided a loudspeaker device comprising left and right channel loudspeaker units of a full frequency range type or a middle and low frequency range type disposed in proximity to each other on a first baffle plane, a loudspeaker unit for a low-frequency sound used commonly for the left and right channels mounted on a second baffle plane which is located forwardly in the direction of propagation of sound from the loudspeaker units from the first baffle plane, and a partition member disposed between said first baffle plane and said second baffle plane and between the loudspeaker units of the respective channels of the full frequency range type or the middle and low frequency range type.
The loudspeaker device of the SD system according to the invention has the following advantages:
1. By providing the partition member between the left and right side loudspeakers, opposite phase components of reproduced sound, particularly those in the middle and low frequency ranges do not cancel each other in the vicinity of the loudspeakers, so that the reproduced sound can be propagated over a broader range whereby reproduction by the SD system can be realized with a high fidelity and a high quality.
2. In a case where a loudspeaker cabinet is adopted in which the left and right side loudspeakers are integrally disposed, the partition member, together with a Saran (TM) net, increases the mechanical strength of the loudspeaker as a whole with resulting improvement in the quality of a reproduced sound.
3. By providing the partition member on the side of the Saran net, the Saran net can be added or replaced on a loudspeaker device which has no such Saran net and, accordingly, an acoustic effect produced by mounting the Saran net can be recognized easily.